The present disclosure pertains to fusers and methods for stripping printed papers from a fusing member.
As is known, in a typical electrophotographic copying or printing process, a charged photoconductor is exposed to form an electrostatic latent image. As described aforementioned U.S. Pat. No. 6,782,233 to Anthony S. Condello et al. (“Condello”), at col. 1, lines 12-41, this latent image is then developed by bringing a developer material such as toner in contact therewith. The toner is deposited as a latent electrostatic image on the photoconductor. The toner image is then transferred from the photoconductor to a copy substrate such as, for example, paper or another media. In order to fix or fuse the toner onto the media permanently by heat, the toner material is heated to cause the toner to flow onto the fibers or pores of the media. Thereafter, as the toner cools, the toner solidifies, thus causing the toner to permanently bond to the media.
Typical fusing arrangements are described in the foregoing Condello patent, especially from col. 1, line 42 to col. 4, line 9.
It is known to use one or more stripper fingers to separate, sever or “strip” a printed paper from a heated fusing member. For example, the aforementioned U.S. Pat. No. 6,963,717 to William R. Klimley et al. depicts in FIG. 1 a fuser stripper baffle 20 comprising individual stripper baffle fingers 10.1 through 10.7 arranged to strip a paper sheet 30 from a fuser roll 10. The stripping process is depicted in FIG. 3.
Further, the aforementioned U.S. Pat. No. 6,785,503 to Youti Kuo et al. depicts in FIG. 4 a set of stripper fingers 30 arranged to lift a printed sheet off a fuser roll 10 near the nip 14 as the sheet passes therethrough.
Further, the aforementioned U.S. Pat. No. 6,782,228 to Kenneth R. Rasch et al. depicts in FIGS. 13 and 14 a plurality of stripper finger assemblies 40 arranged to strip printed papers from the heated fuser roll 12. As described at col. 5, lines 46-56, each stripper finger assembly comprises a base member 42 fabricated from a suitable plastic or metal material. A leaf spring 44 is mounted at one end on the base member 42 and has affixed to its free end a plastic tip 46 that always contacts the heated fuser roll.
Further, the aforementioned U.S. Pat. No. 6,490,428 B1, “Stripper fingers and associated mounts for a fuser in a printing apparatus”, issued 3 Dec. 2002 to Paul M. Fromm et al. depicts in FIG. 5 a plurality of stripper fingers 30 arranged to strip a printed sheet from a fuser apparatus comprising a fuser roll 10 and a pressure roll 12.
Further, the aforementioned U.S. Pat. No. 5,822,668, “Fuser subsystem module for an electrophotographic printer which pivots open for jam clearance”, issued 13 Oct. 1998 to Paul M. Fromm et al. depicts in FIG. 1 one or more stripper fingers 16 disposed across a longitude of fuser roll 12 and arranged to strip printed sheets from the surface of fuser roll 12.
Further, the aforementioned U.S. Pat. No. 5,623,720 to Richard L. Howe et al. depicts in FIG. 4 one or more stripper fingers 104 spring-biased towards a heated fuser roller 54 and arranged to strip printed sheets from the surface of fuser roll 54.
Further, the aforementioned U.S. Pat. No. 4,042,804 to Rabin Moser depicts in FIG. 1 one or more stripper fingers 68 which are arranged to ensure removal of the printed substrate 35 from the fuser assembly 15 as the substrate passes through the nip 34 that is created by the heated fuser roll 30 and the included cooperating pressure or backup roll 33.
Further, the aforementioned U.S. Pat. No. 3,934,113 to Ari Bar-on depicts in FIGS. 4 and 8 a plurality of L-shaped stripper fingers 134 arranged to strip a printed sheet 14 from a fuser assembly 15 comprising a heated fuser roll 30 and a corresponding pressure or backup roll 32 which cooperate to form a nip 33. An alternate form of stripper finger may be employed comprising the stripper fingers 142 as depicted in FIG. 9. See also Bar-on's written description from col. 7, line 32 to col. 8, line 6.
It is also known to use one or more air knives to strip a printed paper from a fusing member. For example, the aforementioned U.S. Patent Application Publication No. 2005/0156377 by Robert M. Jacobs (“Jacobs”) depicts in FIG. 3 a stripper finger 26 that includes an internal pneumatic conduit or air channel 27 therein extending from a flexible hose or other pneumatic connection to conventional or existing machine blower 30. As described in paragraph 0018, this internal conduit or air channel 27 extends all the way out to closely to the stripping edge 27, where this air channel 27 has an upwardly directed opening 28, for blowing air under the leading edge 14 of the printed sheet 12 up away from the fuser roll 24 and towards the normal downstream sheet path in cooperation with the stripper finger 26 stripping edge 27 catching and lifting of that same sheet leading edge 14, thereby effectively increasing the radius of the sheet 12 leading edge 14 in the stripping area which would be created by the mechanical stripper finger 26, thereby reducing the chance of the sheet 12 lead edge folding up and jamming at that location, rather than stripping off into the downstream sheet path, as shown by dot-dashed lines and motion arrows in FIGS. 2 and 3 of Jacobs.
Further, the aforementioned U.S. Patent Application Publication No. 2003/0039491 by Gregory V. Bogoshian (“Bogoshian”) depicts in FIGS. 5 and 6 a corrugating air knife 400. As described in paragraph 0032, the corrugating air knife 400 comprises a manifold 401 that directs a stream of air across the width of the printed sheet 52 as the sheet exits the fuser arrangement comprising the heated fusing roll 62 and the included cooperating pressure roll 64. The air knife 400 includes extra ribs 402 formed which have an air passage integral to the rib 402, as shown in FIG. 5. The localized stream of air flowing from the ribs 402 causes a lightweight paper sheet to corrugate due to the air stream that increases the beam strength of the sheet and prevents the lead edge of the sheet 152 from folding over and wrapping around the fusing roll 62.
Further, the aforementioned U.S. Pat. No. 3,716,221 to Donald J. Gorka et al. (“Gorka”) depicts in FIGS. 1 and 4 an air knife 87 and a stripping and guide blade 88 arranged to strip a printed sheet from the nip area formed between the fusing roller 10 and the cooperating pressure or backup roller 12. See also Gorka's written description at col. 6, lines 31-59.
Currently, papers processed through xerographic printing machines have a tendency to stick to the fusing roll as excessive toner builds up onto the fusing roll. In order to counteract this problem, an air knife is used to help strip the lead edge from the fuser roll. If the lead edge has a problem stripping from the roll then the air knife baffle is supposed to help strip the paper from the fuser roll. Notwithstanding these stripping actions, further stripping improvements are still possible.
Thus, there is a need for the present invention.